Exemplary embodiments of the present invention relate generally to composite products and related methods for manufacturing such products. Composite materials can offer many benefits as compared to natural materials such as wood. However, despite many years of development, there is still a need to improve the formulation, manufacturing, and resulting characteristics of composite materials.
Many composite products are made from virgin materials. However, virgin materials may be in limited supply and/or costly. Thus, there is a need to use at least a portion of recycled material in the formulation of a composite. There is also a need to use at least a portion of recycled material for sustainability reasons and also to potentially earn LEED points.
There is also a need to be able to incorporate a wider range of materials into the composite. The ability to use a broader range of materials (including materials such as lubricants, processing aids, etc.) may facilitate the manufacturing of composite products due to the increased availability of suitable materials. For example, it may be desirable to use different types of recycled material including materials with multiple polymer, filler, and additive materials within the recycled material construction, which may not be an option with typical composites. For another example, one particular material in a multilayer construction may be most important, yet it is still desirable to be able to incorporate the other materials in the multilayer construction to allow for more flexibility in material selection. In addition, the increased availability of suitable materials may help to control the cost of the composite product.
A drawback of typical composites using recycled materials is that the physical characteristics of the composites may lack in comparison to the same composites made with virgin materials. For example, characteristics such as coefficient of thermal expansion, modulus of rupture, modulus of elasticity, moisture sensitivity, peak load, and other mechanical characteristics may be adversely impacted by the use of recycled materials in many common composites. With respect to decking products such as deck planks and rails, the reduction of such characteristics may lead to increased sagging or other types of deterioration. Accordingly, there is a need to be able to use recycled materials and still maintain the same or similar physical characteristics relative to comparable virgin materials.
Additionally, there is a need to improve the manufacturability of composite materials to obtain desirable products. For instance, the use of recycled materials may impact the extrudability of the composite material. It may also limit the adhesion of a cap layer to a substrate.
Furthermore, when exposed to the sun, composite materials can become hot to the touch, especially relative to natural wood. As such, there is a need to transfer heat away from a surface of a composite product and/or minimize the static charge of a composite material. In particular, there is a need to transfer heat away from or otherwise cool the surface of composite decking and railing components.
Present exemplary embodiments may satisfy some or all of the aforementioned needs. An exemplary embodiment may use recycled packaging (e.g., juice pouches or other types of aluminized packaging) or other types of multilayer materials (e.g., films) in the production of a polyethylene, polypropylene, other olefin, or ionomer composite to obtain one or more of the aforementioned advantages. Another example may include metal filler in a composite, which may assist with transferring heat away and/or dissipating a static charge from the surface of a composite product. Yet another embodiment may include polyethylene terephthalate (PET). Thus use of PET may, for example, effectively act as a compatibilizer to allow for the incorporation of a wider range of materials into the composite. In some embodiments, PET may also improve the adhesion of a capstock layer to a substrate. Accordingly, examples of recycled packaging or other multilayer materials may include PET and/or a metallic layer such as may be found in recycled beverage pouches or other liquid containers. While PET may be particularly beneficial, other embodiments may include another polyester instead of or in addition to PET. Further embodiments may include improvements in the incorporation of other ingredients and/or in processing conditions to facilitate manufacturing of the aforementioned composites that have the same, similar, or improved physical characteristics relative to a comparable control.
In certain exemplary embodiments, the inventors have overcome a difficulty in using recycled materials, particularly multilayer materials such as recycled packaging (e.g., juice packs and other types of aluminized packaging). Multilayer materials are often for a single use and disposable, which places a burden on landfills that are nearly filled to capacity. In fact, The Freedonia Group has estimated that approximately one-third of all municipal solid waste in the United States consists of discarded packaging. As such, there is a need to be able to reuse discarded packaging, particularly multilayer plastics.
In many multilayer materials, the combined polymer layers are beneficial for packaging such as for barrier properties, but are difficult to re-utilize. Multilayer recycled plastics cannot be readily separated back into the individual components such as high density polyethylene. In the combined form, certain layers melt at different process temperatures than other polymer layers, and some layers such as an aluminum coating do not melt at all at polymer processing temperatures. There has thus been a difficulty in recycling multilayer plastics (e.g., flexible packaging) due to the combination of different materials in the laminate. Enval, which is based in the United Kingdom, uses microwave-induced pyrolysis technology to separate laminate materials into the individual components. However, this technology is costly, time-consuming, and requires an undesirable amount of energy to achieve the separation of the individual components.
In view of these difficulties, it is surprising that the inventors have identified a class of materials and, for example, a particular combination of polyethylene/PET/aluminum film and other polyethylene, polypropylene, olefin, and ionomer multilayer materials, that may be extruded successfully and also provide desirable performance in wood-substitute products that may be used, for example, in deck boards, railing, fencing, pergolas, residential cladding/siding, and other applications.
In addition to the novel features and advantages mentioned above, other benefits will be readily apparent from the following descriptions of the drawings and exemplary embodiments.